Electrically controlled force amplifier



y 17, 1960 G. CARESANA 2,937,326

ELECTRICALLY CONTROLLED FORCE AMPLIFIER Filed June 16, 1955 2 Sheets-Sheet 1 Inventor G m5 PP8 Care a n4 Attorney Filed June '16, 1955 May 17, 1960 e CARESANA 2,937,326

ELECTRICALLY CONTROLLED FORCE AMPLIFIER 2 Sheets-Sheet 2 Inventor @7383 a A Item e y United States Patent ELECTRICALLY CONTROLLED FORCE AMPLIFIER Giuseppe Caresana, Milan, Italy, assignor to Pio Guardigli, Milan, Italy Application June 16, 1955, Serial No. 515,964 Claims priority, application Italy June 21, 1954 11 Claims. (Cl. 318-31) This inventionrelates to an electric device adapted to transform displacements of forces of minimum amount of a mobile member of a measuring, control or recording apparatus of any kind, constituting a pilot apparatus, into synchronized, equal, similar or anyhow corresponding displacements under the action of forces as great as desired, of a mobile member of at least one piloted apparatus, such as for example a pointer, a delivery regulator, a pressure regulator, any kind of controlled or electric valve for intercepting and for varying the flow of any fluid or the like.

'In this way it becomes possible with very low installation cost to centralize in one single board or panel recording and repeating apparatuses which are equal to one another in all of their electric and mechanical members and which differ only in theindication, scales and values of the respective dials or mobile zones, which refer to the character of the measurements that other apparatuses, placed at any place, may take of the various sources, transmitting them, through the device of the present invention, to the above mentioned recorders and indicators.

Said device is characterized in that it comprises means for actuating the mobile member of the piloted apparatus, which are actuated by an independent power source, and means for controlling said actuating means, contemporaneously linked to the mobile member of the pilot apparatus and to the mobile member of thepiloted apparatus, so as to become operative orinoperative depending on the relative displacements of said members.

According to a further feature of the invention, between the mobile members of the pilot apparatus and of the piloted apparatus there is providedsa coupling with play, adapted to permit relative displacements of said members, thanks to which one orthe other of two electric currents are alternately broken and closed, said circuits being normally open and belonging to a drive unit to which thepilo'ted apparatus vis linked, to displace its mobile member in one sense or in the other one, according to whether the play of the coupling will have accumulated on one side or on the opposite side, until on restoring the play at both sides, both of said circuits will be interrupted'and the mobile memberstof the two apparatuses will be at a standstill.

According to apractical embodiment of the invention said device substantially consists ina particular coupling joint with play formed by a forkwith a contact for each of its inner faces, fixed to the mobile member of one of the two apparatuses, and in a finger belonging to the mobile member of the other apparatus and engaging be tween the two arms of said fork, in such a manner that one of the two contacts can be closed, the fork and finger being movable together along the same trajectory and with a possibility of small relative displacements in the two senses of said trajectory.

The accompanying drawings show diagrammatically by way of nonlimitative example two different modifications of this typical embodiment of the invention; in

said drawings, wherein corresponding members are indicated with the same reference numerals:

Fig. 1 represents in perspective view one first embodiment of the device, for the case of apparatuses with mobile members rotatable about an axis.

Fig. 2 shows in analogous manner another embodi-- ment thereof, for the case of apparatuses with mobile members having translatory movement.

In the case of Figure 1, on the spindle 1 connected to the mobile pointer 2 of the pilot apparatus 3, there is mounted rotatably a small cylinder 4 whose end facing. the pointer 2 has a V-shaped cam-profile so that it can receive and retain in its recess a small rod 5 integral with the spindle 1 by the combined action of a helical spring 7 acting upon the hub 6 of .the small cylinder 4; from the small cylinder 4 there projects the contact finger 8. The shaft 9 is coaxial to the spindle 1. On the shaft 9 there are fixed a collector 12 and indirectly two conductive arms 13 and 14 forming a fork and between which there is placed the finger 8, which on coming at contact with the one or the other arm, determines the closing of one or the other of the circuits of the electric motors 15 and 16 which have the task of causing to rotate in reverse sense the control common axis 17 of the piloted apparatus, carrying also the drum 19 whereon there is placed the braking shoe 20 controlled by the solenoid 21. The drive shaft 17 is coupled at one side to the shaft 9 by means of a reducer 10 and at the other side to the pointer 11 of the piloted apparatus, through a second reducer 18. A group of relays of known kind may be connected on the electric circuits of the apparatus for a better control of their closing and opening and if necessary for the control of the other piloted apparatuses.

The working of the apparatus is as follows:

Assuming the pointer 2 of the apparatus is at a standstill, also the finger 8 remains vat standstill and detached from the two contacts 13 and 14. All of the electric circuits are open and the shoe 20 presses with its own Weight against the surface of the drum 19.

If now the pointer 2 moves according to the arrow 23, also the small rod 5 and the small cam-cylinder 4 will move in the same direction taking the finger 8 to close the electric circuit through the cont-act 14, to operatethe electromagnet 21, which attracts the shoe20 releasing the drum 19, and to start e.g. the electric motor 16 which through the reducers 18 and 10 displaces contemporaneously the pointer 11 and the shaft 9 until the contact 14 detaches from the finger 8 thus breaking the circuitjthe electromagnet 21, which has remained de-energized, releases the shoe 20 which by effect of its own weight acts as a brake upon the drum 19, stopping the motor 16 and therewith the whole assembly.

If the pointer 2 instead moves in-the sense indicated by the arrow 24, the finger 8 comes into contact with the arm 13 through which again the circuit energizing the electromagnet 21 is closed, which detaches the shoe 20 from the surface of the drum 19 whilst the motor 15 is fed. and rotates the shaft '17 inthe sense opposite the sense with which it is rotated by the motor 16. The shaft 9 then will turn in the sense of arrow 24 untilthe arm .13 detaches itself from thefinger 8'so as to break the circuit, consequently stopping thev whole device; at the same time, also the pointer 11 will have moved together with the pointer 2.

In the event that the piloted device power should beinterrupted to the motors 15 and 16 because of delay in relay closing or any other reason, the pilotapparatus 3 can continue working even if the finger 8 is locked be tween the immobilized arms 13 and 14. As the shaft 1 turns, the small rod 5 projecting from theshaft 1 will run on the V-shaped cam-profile of the; cylinder 4 which slides in the direction of arrow f along the spindle 1 overcoming the action of the spring 7.

When the motors 15 and 16 are again supplied with power the arms 13 and 14 are displaced thus permitting the finger 8 to displace itself as well, and the spring 7 can cause cylinder 4 to slide back in the direction of arrow 1" until the small rod 5 reaches the deepest point of the V-shaped cam-profile.

Besides the function above described, the small camcylinder 4 has also the task of keeping up a stability of practically continuous contact during the whole period in which there occurs a displacement in the pilot apparatus and in the piloted apparatus; indeed a greater angular displacement'of the spindle 1 in respect of the shaft 9 can be compensated thru a relative rotation of the small rod 5 in respect of the small cam-cylinder 4, so as to accumulate the difference to be returned then to the piloted apparatus, as soon as the speed of rotation of the spindle 1 begins to be lower than that of the shaft 9. From the foregoing it appears clear, that the small cam-cylinder 4 acts as an accumulator of displacements to be re-transmitted to the piloted member as soon as the kinematic conditions will allow it.

With apparatuses having mobile members with translatory movement (Fig. 2) the linking system according to the invention is not very different from the above described one.

The finger 8 is associated in this case with a slider 1 of the pilot apparatus 3 which is equipped with a pointer 2 slidable in front of a straight-lined graduation; said finger 8 can play between the contacts 13 and 14 carried by a rack 9 movable parallel to the slider 1 and with which is integral the pointer 11 of the piloted apparatus. The finger 8 and the contacts 13 and 14 terminate as in the case of Fig. 1, the circuits of the motors 15, 16 which turn in opposed senses so that the closing of one or the other of said circuits through the contact 13 or the contact 14 rotates in one sense or in the other the worm-screw 18 which transmits the movement to the helical gear-heel which in turn by way of the pinion 25 transmits it to the rack 9'. Things are arranged in such a way that while the pointer 2 of the pilot apparatus moves according to the arrow 23 or according to the arrow 24, also the pointer 11 moves in the same sense and by the same amount.

However, Fig. 2 illustrates also the possibility of using a reducer 18 connected to the drive shaft 17 to repeat the displacement of translation of the pointer 2 of the pilot apparatus 3, transformed into an angular displacement of the pointer 11' of a piloted apparatus.

It should be understood that there may be other practical embodiments of the device according to the invention, different from those hereinbefore described without departing from the scope of the invention, and there may be dilferent applications as well.

In any case, the displacement of the pointer 11 of the piloted apparatus may be obtained with couples of moment as great as desired. These depend on the power of the motors employed to actuate said apparatus, so that said displacement may be utilized not only to repeat measurements, but also as an automatic drive means for various machines.

So, e.g. the linking may be obtained, besides direct coupling through the special joint also through a remote control wherein an apparatus directly linked to the pilot member by means of the special joint, permits other equal apparatuses in synchronism therewith to be operated by remote control from the pilot apparatus. Said remote controlled apparatuses linked thereto to depend thereon can be embodied fundamentally with synchronous electric motors coupled to a reducer with electro-magnetic stop or with electromagnetic locking or barring gears operated by pulses.

- Otherwise, said remote-control linking may be obtained with a system of repeaters coupled with servomotors; the

usual servo-motor apparatus will be coupled in the manner described to the pilot apparatus, for remote-control, by means of the variation of capacity, inductance, resistance or other electric quantities, of the repeating appa ratuses, each of which may in turn be linked in the manner described, to a servomotor; in this case the motors of the repeaters may be asynchronous motors, not needing to run in synchronism.

Having thus described my invention what I claim as new and desire to protect with Letters Patent is:

l. A torque amplifier comprising a controlling member, a controlled member to be maintained in synchronism with said controlling member, electric drive means for said controlled member, first electric contact means displaceable in response to movement of said controlling member, second contact means cooperating with said first contact means and displaceable in response to movement of said controlled member, electric circuit connections between said first and second contact means and said drive means, to operate said drive means in either direction upon corresponding displacement of said controlled member relative to said controlling member, whereby to maintain said controlled member in continu ous follow-up relation to said controlling member, and slipping clutch means between said controlling member and said first contact means.

2. A torque amplifier comprising a controlling member, a controlled member to be maintained in synchronism with said controlling member, electric drive means for said controlled member, first electric contact means displaceable in response to movement of said controlling member, second contact means cooperating with said first contact means and displaceable in response to movement of said controlled member, electric circuit connections between said first and second contact means and said drive means, to operate said drive means in either direction upon corresponding displacement of said controlled member relative to said controlling member, whereby to maintain said controlled member in continuous follow-up relation to said controlling member, and slipping clutch means between said controlling member and said first contact means, to accumulate the displacement thereof during temporary immobilization of said controlled member and to effect subsequent recovery of displacement of said controlled member to restore the synchronism with said controlling member.

3. In a device as claimed in claim 1, in which said first contact means is comprised of a contact responsive to movement of said controlling member and said second contact means is comprised of a pair of contacts each arranged on one side of said first contact and operatively connected to said controlling member, whereby said controlled member includes brake means responsive to said controlling member for holding and releasing said controlled member.

4. Electro-mechanic torque amplifier comprising in combination: a controlling shaft controlled by a mobile member of a pilot apparatus, a controlled shaft for the control of the mobile member of a piloted apparatus, at least one independent power source to control the rotation in both directions of said controlled shaft, means responsive to the relative rotation of said controlling shaft and said controlled shaft for starting said power source in one direction or the other, thus synchronizing the two shafts, and stopping means for the controlled shaft working in response to the interruption of said power source, said means responsive to the relative rotation of the controlling shaft and the controlled shaft consisting of a pair of contacting arms forming a fork carried by the controlled shaft and of a contact fixed to a finger carried by the controlling shaft and placed between the contacting arms of said fork, said finger being slidably mounted on said controlling shaft against the action of a spring, and means for rotatably coupling said finger and said ass-mac controlling shaft being automatically disengageable upon immobilization of said controlled shaft.

5. In a torque follower having a controlling member, a controlled member to be maintained in synchronism with said controlling member, electric drive means for said controlled member, first electric contact means displaceable in response to movement of said controlling member, second contact means cooperating with said first contact means and displaceable in response to movement of said controlled member, electric circuit connection between said first and second contact means and said drive means, to operate said drive means in either direction upon corresponding displacement of said controlled member relative to said controlling member to maintain said controlled member in continuous following relation to said controlling member, a shaft positively connected to said controlling member, a sleeve axially and rotatably movable upon said shaft and connected to said first electric contact means, a V-groove at the end of said sleeve, a stop rod radially projecting from said shaft adapted to be seated in said V-groove, and means biasing said sleeve against said stop rod whereby rotation of said shaft produces rotation of said sleeve and axial movement of said sleeve when rotation of said sleeve is restricted.

6. In a torque follower as set forth in claim 5, a flange on said sleeve, said means biasing said sleeve against said stop rod being a spring connected to said flange.

7. In a torque follower having a controlling member, a controlled member to be maintained in synchronism with said controlling member, electric drive means for said controlled member, first electric contact means displaceable in response to movement of said controlling member, second contact means cooperating with said first contact means and displaceable in response to movement of said controlled member and electric circuit means between said first and second contact means to operate said drive means in either direction upon corresponding displacement of said controlled member relative to said controlling member to maintain said controlled member in continuous following relation to said controlling member, said controlled member including brake means responsive to said controlling member for maintaining and releasing position of said controlled member.

8. A torque follower as set forth in claim 7 wherein said brake means include a solenoid responsive to current in said controlling member.

9. A torque follower as set forth in claim 8 wherein said brake means further include brake shoes responsive to said solenoid.

10. In a torque follower as set forth in claim 9 clutch means between said controlling member and said first contact means.

11. A torque follower as set forth in claim 7 wherein said motion of said first and second contact means is translatory.

References Cited in the file of this patent UNITED STATES PATENTS 2,273,632 Floraday Feb. 17, 1942 2,440,838 Yardeny May 4, 1948 2,523,584 Miller Sept. 26, 1950 FOREIGN PATENTS 346,895 Germany Jan. 10, 1922 687,149 Germany Jan. 24, 1940 

